Work machines such as excavators use a variety of work attachments. These attachments include buckets, graders, grapples or drilling attachments.
It is desirable to have a releasable attachment between the construction vehicle and the work attachment to easily and rapidly change the work attachment.
Generally, a releasable attachment is provided by two or more jaws which engage pins on the work attachment. At least one of the jaws is moveable in a pivotal or sliding motion.
The first jaw receives a pin and the second jaw moves to engage the second pin.
An actuator forces the jaw against the pin. This retains the pin in the jaw thereby securing the work attachment to the machine.
It is known to use a locking portion as an added safety measure. This secures a pin in a jaw.
In one form of coupling a person manually inserts a member to act as a locking portion. However, this involves the operator getting out of the excavator and getting close to the work attachment.
There are alternate embodiments where a locking portion is operatively coupled to the moveable jaw. In these, movement of the jaw controls movement of the locking portion to either retain or release a pin from the other jaw.
An improvement to the commonly available coupling assemblies is that disclosed in PCT Application No. NZ2007/000320 to JB Sales International Limited.
The JB Sales patent discloses a coupling having a body on an excavator arm with two jaws to receive pins on a work attachment. One of the jaws is slidable with respect to the body so that it can engage a pin on the work attachment.
The slideable jaw is configured to control a pivotally mounted retention member. This member therefore retains a second pin when the first jaw is not actuated to a position beyond that it assumes when receiving the first pin.
Due to the opposite facing of the jaws, the mounting must be tilted to allow the second jaw to extend beyond the locking position.
However, the assembly disclosed by the JB Sales patent has a number of limitations.
One of these disadvantages is the mounting of the retention member to the body. Over time the pressure exerted on the retention member by the moveable jaw causes wear and tear. The retention member may therefore be prone to failure.
In addition, the retention member only secures a second pin in the second jaw when the first jaw is in the correct position. Due to this securing the work attachment to the mounting is dependant on the position of the moveable jaw. Should the actuator or moveable jaw fail with the coupler in an inverted position, the effectiveness of the retention member is compromised, and this could pose a safety risk.
A further disadvantage of the JB Sales patent is that the pin is not secured in the jaw immediately at being inserted into a jaw. Rather the operator must elect to retract an actuator so that the retention member secures the pin inside the jaw. This is an issue as research indicates that most accidents involving the accidental dropping of a work attachments occur during the connection process. The JB Sales patent therefore does not address a major safety issue with releasably connected work attachments.
Further, more stringent safety regulations (presently in a draft form) would make it useful to have a release mechanism requiring more than three stages. This is because forcing an operator to take additional steps may help to ensure that work attachments are not accidentally released from an excavator.
Ideally, this assembly should be more durable and less prone to mechanical failure than coupling assemblies available.
When in use, a boom arm controls the position and most of the operative movement of the work attachment. However additional actuators are used to provide more control over movement of the work attachment. This may include the tilting action of a bucket, or to operate a drilling machine.
These actuators are generally secured on the work attachment. Therefore, it is necessary to have a releasable connection between the actuators on a work attachment, and a control system. Generally, this occurs using complementary hydraulic hose connectors on the work attachment and boom arm.
Connecting the complementary connectors is a manual process requiring an operator to switch off the excavator to relieve residual oil pressure and then climb out of the excavator to connect by hand.
Therefore, it would be an advantage to have an assembly which automatically aligns and locks connectors. Further, that assembly should allow them to release each other when required.
Yet another disadvantage of the available connectors in the prior art is that they are exposed when not in use. They can therefore be knocked causing damage or contaminated by the ingress of dirt. This may result in sealing issues, leading to the escape of oil from the connectors. It can therefore affect the overall performance of the connectors.
It would be an advantage to have a system to protect connectors from these types of damage.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.